Database Software

I seem to be running into a problem. (I'm still very new to RMAN so forgive me if this question is overly simple.)

A client of ours is running Oracle 10g (under Windows 2000 Server.) Currently they use RMAN to perform regular database backups. However, when testing the restore procedures on their backup server, we began to get the error:RMAN-06023: No Backup Or Copy. (The restore procedures had worked in the past, but somewhere along the line they stopped working.)

The RMAN backup looks like this:
run {
backup (database include current controlefile );
backup (archinvelog all delette input );
}
allocate channel for maintenance device type disk;
delete noprompt obsolete device type disk;
release channel;

The restore procedure that we had been using is as follows:
- delete the database using dbca
- set the oracle sid
- use sql plus to drop the diskgrop
- use dbca to configure the disk groups and set disk passwords
- create the adump, bdump, dump files under the admin directory
- set the ORACLE_SID
- use oradim.exe to configure startup setting
- copy the PWDxxx.ora on the main server file to the 'database' directory on the backup server
- Startup RMAN via "RMAN TARGET /"
- Set the DBID on the backup server to match the production server
- Startup force nomoount;
- restore spfile from '<my backup file>';
- starup force nomount;
- restore controlfile from '<mybackup file>';
- Alter database mount;

Now, up until that point, everything seems to go OK. However, when I try to run: RESTORE DATABASE; I get the following errors:

RMAN-06026: some targets not found - aborting restore
RMAN-06023: no backup or copy of datafile 4 found to restore
RMAN-06023: no backup or copy of datafile 3 found to restore
RMAN-06023: no backup or copy of datafile 2 found to restore
RMAN-06023: no backup or copy of datafile 1 found to restore

The originating server has 7 tablespaces: system, undotbs, sysaux, temp, users, and 2 containing actual user data.

Now, when I do a 'list backup' it appears that there are 6 data files available. As expected, there is nothing for 'temp'. it appears that the 2 tablespaces containing user data are in datafile 5&6, and those were restored properly. The ones that weren't restored were for the system, undotbs, sysaux and users tablespaces. (I get the same error if I try to restore datafiles 1-4 individually.)

Anyone have any ideas about what the problem could be? (I've been searching through the posts; I've found others have had this error, but the details of their problems differ from mine.